The problem is that practical advice is often misinterpreted or misconstrued.

“the idea that a person can’t eat more while exercising”

You can, of course, eat more while exercising.

But you can’t eat much more while exercising, because running while eating is a choking hazard.

I’m kidding, but that is the nature of what I’m getting at.

But really–you can’t eat much more during the day because exercising just doesn’t burn much more calories. And eating a lot more calories is relatively trivial.